Gradle.Enemy at the gates

Gradle.Enemy at the gates.

Сергей Моренец, morenets@mail.ru

23 мая 2014 г.

About author• Works in IT since 2000

• 10 year of Java SE/EE experience

• Migrated to Gradle after 7 years of Ant/Maven

usage

• Regular speaker at Java conferences

Agenda

• Builds tools overview

• Gradle under the microscope

• Examples

• Q & A

Lost in selection

Magic pill

Gradle• Flexible yet model-driven JVM-based build tool

• Acknowledges and improves on the very best ideas

from Make, Ant, Ivy, Maven, Rake, Gant, Scons, SBT,

Leinengen, and Buildr

Gradle

• Flexibility of Ant

• Dependency management from Ivy

• Intelligence of Maven

• Speed and hashing of Git

• Metaprogramming power of Groovy

Apache Ant• Offers extreme flexibility

• Imposes no convention

• Lightweight dependency management

Apache Ivy• Cross-platform dependency management

• Transitive dependencies

• Enhanced support of repositories

Apache Maven

• Offers rigid standards and support for dependency

management

• More difficult and inflexible standards/procedures

• Declarative approach

Issue #1. XML

• Large and complex files are hard to understand

• Hierarchical structure limits the expressiveness

of the format

• Good format for the data and complex for the flow

Issues #2. Frameworkitis

• Frameworkitis is the disease that a framework wants

to do too much for you or it does it in a way that

you don't want but you can't change it

• The bigger the framework becomes, the greater the

chances that it will want to do too much, the bigger

the learning curves become, and the more difficult

it becomes to maintain it

• Group of small frameworks(toolkits) is better than

big framework

Solution #1. Groovy

• An agile and dynamic language for the Java

Virtual Machine

• Makes modern programming features available to

Java developers with almost-zero learning curve

• Provides the ability to statically type

check and statically compile your code for

robustness and performance

• Supports Domain-Specific Languages and other

compact syntax

• Every Gradle build file is Groovy script

Gradle

• First release in Apr 2008

• Current version 1.12 released in April 2014

• Used in Carrier, EADS, Hibernate, Grails, Groovy,

Spring-Security and Spring-Integration

Hans Dockter• Founder of Gradle and Gradleware

• 13 years of experience as a software developer,

team leader, architect, trainer, and mentor

• Previously worked at Jboss and founded Jboss-IDE

• Holds a Diploma in Physics with a minor in Computer

Science

• Admirer of domain-driven-design

Slogan

• Make the impossible possible

• Make the possible easy

• Make the easy elegant

Gradle overview

• A flexible general purpose build tool

• Declarative builds and build-by-convention plugins

on top

• Multi-project support

• Powerful dependency management based on Ivy

• Programming tool

• Based on Groovy

• Gradle is written in Java with a Groovy DSL layer on

top

Build structure

• Gradle build consists of one or more projects

• Project contains one or more tasks

• Task is fundamental unit of build activity

• Tasks are named collections of build instructions

• Tasks are the equivalent to Ant targets

• Task is made up of actions

Hello world

• $ gradle helloWorld

build.gradle

Maven pom

Build phases

Execution

Configuration

Initialization

Initialization

• Gradle defines which projects are involved in build

• Project instance is defined for each involved

project

Configuration

• Task objects are assembled into an internal object

model, usually called the DAG

• The build scripts of all projects which are part of the

build are executed

• If “configuration on demand” feature is enabled

then only relevant projects are configured

Execution

• Gradle determines the subset of the tasks, created

and configured during the configuration phase

• Subset of tasks depends on the gradle command

argument and the contents of the current directory.

• Selected tasks are executed in the order required

by their dependency relationships

DefaultTask

• dependsOn(task)

• doFirst(closure)

• doLast(closure)

• onlyIf(closure)

Sample project

Sample project

Dependent tasks

Task types

Copy Jar

JavaCompile JavaExec

JettyRun War

Custom task

• Writes audit information at the end of the build

• Audit information includes project name and build

timestamp

• Audit files are located in the separate folder

Custom task

Custom task

Custom task

Custom task

Multi-project builds

• Build where you build more than one project during

a single execution of Gradle

• Sub-projects should be defined in settings.gradle

• Settings file is analyzed in the initialization phase

when sub-projects are revealed and included into

DAG

• Sub-projects are sub-directories in the simplest case

settings.gradle

Plugin

• Reusable pieces of build logic

• Can be used in different projects/builds

• Can be written in Groovy, Java or Scala

Plugin• Add tasks to the project

• Pre-configure added tasks with useful defaults

• Add dependency configurations to the project

• Add new properties and methods to existing type

via extensions

Plugins

• Android

• AspectJ

• Flex

• Grails

• GWT

• JavaScript

• JAXB

• Jenkins

• SvnKit

• Tomcat

• Xslt

Plugin import

Packaging

• Build script

• buildSrc project

• rootProjectDir/buildSrc/src/main/groovy

• Standalone project

Custom plugin

Custom plugin

Custom plugin

Custom plugin

• $ gradle writeBuild

Custom plugin

Integration• Ant

• Maven

Gradle and Ant• Gradle is often described as Groovy-based Ant.

• Competitor of Gant(Groovy Ant scripting)

• Share DAG concept

• Gradle tasks are similar to Ant targrets

• Gradle variables(typeless) are close to Ant

properties

Hello Ant

Ant import

Gradle and Maven

Gradle and Maven

Maven Coordinate Gradle Property Gradle Default

groupId group blank

artifactId name Project directory name

version version unspecified

name N/A N/A

description description null

Comparison

Operation Gradle Maven

Build(sec) 21,2 24,2

Inc build(sec) 8,7 11

Build with tests(sec)

29 28

Clean(sec) 3,9 3,1

Distributive(Mb) 44 3

Maven converter

• Create build.gradle file in the root folder

• Specify apply plugin: 'maven2Gradle' in the

build.gradle file.

• Run gradle maven2Gradle

Maven Dependencies

Scopes:

• compile

• provided

• runtime

• test

• system

• import

Dependencies

Gradle Dependenciesconfigurations:

• compile

• default

• testCompile

• testRuntime

• archives

• runtime

Scope flexibility

Repositories• Gradle provides a bridge implementation to Ivy- or

Maven-formatted repositories

Profiles• build.gradle

• dev-profile.gradle

• test-profile.gradle

• $ gradle –Pprofile=dev build

Resource handling

Resource handling

Unit testing• Junit

• TestNG

• Spock

• Geb

• EasyB

Skip tasks

• $ gradle -PskipTests

Skip tasks

Skip tasks

Caching

• Gradle caches all compiles scripts by default

• Compiled scripts are put into .gradle folder

• Gradle uses compiled version if the script hasn’t

changed

• --recompile-scripts option discards cache

Practical tasks

• Multiple projects

• Liquibase

• Deployment

Multiple projects

• Huge project

• Multiple sub-projects/pom.xml files

• Complicated maintenance

Liquibase

• Plugins for 2 and 3 versions

• Lightweight front-end for Liquibase command-line

• Gradle task for each Liquibase command

Deployment

• Separate plugins for Jetty/Tomcat

• General plugin for multiple containers

Pros• Native Java interaction

• Ant/Maven integration

• Transitive dependency management(based on

Maven/Ivy)

• Multiple third-party plugins(70+)

• Incremental builds

• Rapid development

Cons

• Less efficient due to script nature

• Large learning curve

• Less community & industry support

Future• Testing toolkit for integration into business logic

• Improved plugin portal and plugin development

• Execution of Maven builds/plugins at runtime

• Distributed testing

• Parallel and distributed execution

… to be continued

Resources

Practice

• https://github.com/hibernate/hibernate-orm

• https://github.com/SpringSource/spring-framework

• https://github.com/gradle/gradle

Q&A

• Сергей Моренец, morenets@mail.ru